In-depth Analysis of the Four Mainstream CVD Technologies

1.Atmospheric Pressure Chemical Vapor Deposition (APCVD)

Process characteristics: It is carried out under normal pressure (atmospheric pressure), and the reaction system is simple and the deposition rate is fast. However, the film uniformity and step coverage ability are relatively poor, and it is easy to produce particle pollution due to the influence of vapor phase reaction.

Core Applications:

Cryogenic Oxides: Applications that are sensitive to thermal budgets.

Doped/undoped silicon glass: used for early dielectric layer filling epitaxial layer deposition: growth of a single crystal silicon layer on a specific substrate.

Technical status: Due to process limitations, the application in advanced processes has decreased, but it is still used in some flattening or thick film deposition that does not require extremely high film quality.

Low-pressure chemical vapor deposition (LPCVD)

Process features: Performed at lower pressures (0.1-10Torr) and higher temperatures (450°C-900°C). The low pressure reduces vapor phase nucleation, resulting in superior uniformity, density, and step coverage of the membrane. The disadvantage is the slower deposition rate and high temperature.

Core Applications:

Polysilicon: Key materials for gates and local interconnects. Silicon nitride: excellent barrier layer, etch stop layer, and hard mask.

High temperature oxide: high-quality dielectric layer Tungsten: for filling of contact and through holes.

Technical status: It is a cornerstone process for high-quality, critical thin film deposition, especially irreplaceable in steps that require high-temperature heat treatment.

Plasma-enhanced chemical vapor deposition (PECVD)

Process characteristics: Plasma is introduced to achieve thin film deposition at low temperature (200°C-400°C) using its high activity. It perfectly solves the problem of damage caused by high-temperature processes to the structure of existing devices.

Core Applications:

Insulation on metal: Deposits a protective dielectric layer on the formed metal interconnects. Low K media: Reduces RC latency and increases chip speed.

Passivation layer: Final protection of the finished chip. Pre-metal media: Provides a flattening basis for the first layer of metal interconnects.

Technical status: The most widely used CVD technology is the key to realizing multi-layer interconnect structures, and has become the main force of back-end processes due to its low-temperature characteristics.

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Technical comparison and summary

Process pressure	Press Temperature	Membrane quality	Gap filling capacity	Main application scenarios
APCVD	Normal	Mid-High	Common	Bad	Thick film, epitaxy, non-critical layers
LPCVD	Low                             High		Perfect                    Good                        Polysilicon, silicon nitride, critical barrier layer
PECVD	Low	Low	Good	Good	Insulation layer on metal, passivation layer, low K medium
HDPCVD	Low                            Mid                        Perfect                   Perfect                              STI, high aspect ratio gap filling

In the chip manufacturing process, each of these four CVD technologies performs its own role: LPCVD is responsible for laying the high-quality infrastructure.

PECVD lays a wide range of dielectric and protective layers in back-end low-temperature environments

HDPCVD specializes in tackling the most difficult topology filling challenges in advanced processes. APCVD gives full play to its advantages of rapid deposition in specific fields.